Asynchronous fetching seems to be working
Coolness. Straw is actually successfully fetching the dozens of feeds I'm reading, asynchronously, without the troublesome network thread. DNS lookups with ADNS (ha, yes, another dependency), reading stuff off network via asyncore. And the UI is pretty responsive. It's still slower than it used to be, but I think that's a tradeoff I can make. And, as I said earlier, things can possibly be tuned to work out better.
However, one somewhat serious usability problem remains: the stuff is basically fetched off a queue, where things go like this: request an URL -> resolve the host asynchronously -> add the split URL + IP to the fetching queue -> fetch data asynchronously -> stuff the results into the internal datastructures. Now, when you press 'g' or when the timer triggers a polling run, we request all the RSS URLs, then when we have finally gotten something, we parse it, see if there are any images, and request those. See the problem? Unless name lookups are in some cases seriously slow, all the articles are fetched before any of the images. I suppose that's fine if you are interested only in the text, but if not, and you are sitting in front of your aggregator, waiting to read the words of the bloggerdom hot off their keyboards, you get to read the items without images.
So maybe I should prioritize the images higher. That is, stuff the image requests to the front of the queue. And I suppose that as long as we are talking data structures instead of, say, things you see in Helsinki in front of bars Friday and Saturday evenings, it won't be a queue any longer. Oh well. That's theory for you.